Method of and means for introducing potassium or other vapors in lamps



Dec. 15, 1925- 1.565.564

A. M. HAGEMAN 1 METHOD OF AND NBANS FOR INTRODUCING POTASSIUM OR OTHERVAPORS IN LAMPS Filed July 23, 1923 INVENTOR AARON M. HAGENAN ATTORNEYPatented Dec. 15, 1925;

UNITED STATES PATT oFFicE.

AARON MARTIN HAGEMAN, OF BLOOMFIELD, NEW JERSEY, ASSIGNOR TO WESTINGHOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA.

METHOD OF AND MEANS FOR INTRODUCING POTASSIUM OR OTHER VAPORS IN LAMPS.

Application filed July 23, 1923. Serial- No. 653,116.

To all whom it may concern:

Be it known that I, AARON MARTIN HAGE- MAN, a citizen of the UnitedStates, and a resident of Bloomfield, in the county of Essex and Stateof New Jersey, have invented a new and useful Improvement in Methods ofand Means for Introducing Potassium or Other Vapors in Lamps, of whichthe following is a specification.

This invention pertains to electric lamps of the gas-filled type and hasmore particular reference to a method of and a means for theintroduction of a free alkali metal into neon lamps.

It is an object of the invention to provide a practical and efficientmethod of introducing an alkali metal such as potassium into an electricdischarge device or other evacuated or gas-filled container to act as agetter and to reduce the electrode voltage drop.

It is another object to devise a means by which an alkali metal such aspotassium may be easily and readily introduced within an evacuated orgas-filled container.

Other objects will become apparent from the description and claims andfrom the drawing in which the figure is an elevation of a discharge lampof the gas-filled type embodying the'invention.

It is well known that the starting and op,- erating voltages of neon orother gas-filled glow lamps may be much reduced by the introduction ofan alkali metal therein. The best results have been obtainedby the 85use of potassium in vapor form, which seems to increase the ionizationbetween or the electron discharge of the metal electrodes as well as toreduce the resistance of the gap between \hem. This is, however, but a40 theory of the principal cause of the peculiar phenomenon that takesplace upon the intro duction of a vapor of an alkali metal into thistype of discharge lamp.

Considerable difiiculty has been encoun- 45 tered in using metals of theclass. of potassium since their low melting points and susceptibility tooxidation or combination with other metals or compounds destroys theirusefulness as voltage drop reducers and clean-up agents and renderstheir manipulation by the usual methods and means extremely dangerous.Potassium for instance with a melting point of 62 C. will readily takefire from contact with the human skin making it necessary to use costlyapparatus and methods to properly handle it.

I find that an amalgam of mercury and potassium may be so prepared inthe solid state that a condition of reduced activity is reached in whichcondition, the amalgam may be cast into pellets of a desired size andshape and introduced into the lamp or other device before the potassiumcan react with the moisture and gases in the surrounding atmosphere.Such an amalgam may be prepared by heating pure mercury to from 65 to 70C., which is above the melting point of potassium (62 C'.) and, by

means of a pair of tweezers, immersing small pieces of clean and purepotassium beneath the surface of the heatedmercury. The potassium willmelt and rapidly form a liquid potassium-mercury amalgam with the 0-tassium thoroughly and homogeneously incorporated with the mercury.Stirring may help to completely diffuse the two metals. By this methodit was found possible to obtain an amalgam having a softening point ashigh as 110 C.

Amalgams containing varying percentages of potassium may be readilyprepared by this method but I may prefer to use an amalgam containing 2%of potassium for neon glow lamps. Difficulty may be experienced inpreserving the amalgam in pellet form in the open atmosphere although itmay be readily introduced within a lamp and maintained in a solidcondition during the process of manufacturing the lamp if reasonablyprotected from heat during the sealing-in and exhaust operations.

In introduciing the amalgam into the lamp I prefer to secure it to aportion of the interior structure in some suitable manner. For instanceas is illustrated in the drawing, I may secure a cup 2 of suitablematerial to the terminal of one of the non contacting electrodes 4;, 6,which are secured in the usual manner to lead-in wires 8 and within theusual bulb 10. The cup may be made of copper or any material not readilyattached by the potassium, suitable for the purpose and is attached tothe end of the electrode in any desired manner; The cup may be packed orfilled with the prepared amalgam and may be positioned in any mannerdesired with respect to the sealing-in and exhausting operations as themercury of the potassium amalgam readily amalgamates with copper andadheres to the cup, if the cup be made of such metal as copper, withsuflicient tenacity to prevent it from being jarred out. Any heatreflected from the sealing-in or tipping operations toward the cup isconducted over the wire electrodes, which act as a heat shield, andthereby dissipate the heat.

After the lamp or other vessel is ex-' hausted, neon or other gas orgases, suitablefor the purpose, may be introduced in i any manner knownin' the art. The alkali metal is volatilized by application of heat fromthe exterior or by' connecting the electrodes across a source of ower ofsut ficient potential to cause s cient heating of the electrodes tovolatilize it. Other methods of volatilizing the alkali metal such as byhigh frequency inductive heating of the amalgam by eddy currents inducedtherein, may be resorted to as will be readily apparent. It may bepreferable to cold exhaust the lamp' and if this be done, it may benecessary to treat 'out'any occluded gases from the electrodes prior totheir assembly in the lamp structure.

While this invention has been described particularly with reference tothe introduction of potassium-into neonlamps, it is to be understoodthat it is not so limited but broadly comprehends the manipulation ofthe alkali metals in such manner that they may be readily introducedintoevacuated or gas-filled containers of various types and readily handlefor anydesired purose. I do not limit myself therefore to the particularform or structure shown as many modifications of the invention willpresent themselves without departin from its spirit or from the scope oft e appended claims.

What is claimed is:

1. The method of introducing a free alkali metal into an electricaldischarge device which comprises preparing a relatively high meltingpoint amalgam of said metal, and

introducing-the amalgam in the said device in contact with a metal partof the device. (1

.2. The method of introducing the vaporof an alkali metal into, anelectrical discharge device comprising introducing .a

relatively high melting point amalgam of said metal into said device incontact with a metal part thereof and vaporizing said alkalimetal.

3; The methodof introducing the vapor of an alkali metal into anelectrical is-' charge deviie comprising introducing an amalgam of saidmetal having a relatively high melting point into said device inconwhich consists in mixing said metal with 'mercury and applying themixture as an amalgam to a metal part of the device. 6. The method ofintroducing an alakli metal into a discharge device consisting inapplying said metal in the form of a mercury amalgam to a copper bodyand introducing the copper body into the device. 7. The method ofintroducing potassium into a discharge device having metal electrodes..consisting in attaching a copper body to one of said electrodes andapplying potassium in the form of an amalgam to the copper body.

8'; The method which comprises positioning an amalgam of anunstablemetal on a metal portion of the device-in proximity to the path ofdischarge and causing a discharge whereby said unstable metal isvolatilized.

V of reducing the starting a voltage of gas-filled discharge devicesprising, supporting an amalgam of an un-' stable metal within saiddevice, from a metal part thereof in the vicinity of the path ofdischarge and causing a discharge whereby said unstable metal isvolatilized.

10. A commercially unfinished gas filled electricdischarge device havingsolid electrodes and means including an alkali metal in a relativelystable state attached to one of said electrodes by mercury andcooperative therewith whereby said alkali metal is rendered unstableupon the passage of a current between said electrodes.

11. The) method of introducing an alkali metal into a discharge devicewhich consists in forming an alloy of the metal which. will adhere tometal at normal temperatures and applying said alloy to a metal part ofsaid evice prior to the sealing of sald part into the device. V

12. The method of introducing an alkali metal into, an evacuatedcontainer which consists in' forming an amalgam of the Ill metal,applying the amalgam to another metal with which the mercury of theamalgam readily amalgamates and introducing said last mentioned metalinto thedevice.

13. The method of introducing an alkali metal into an electricaldischarge device consisting in applying said metal in the AARON MARTINHAGEMAN.

